This invention relates to an ink supply system for an ink jet printer and more particularly to an ink supply reservoir which acts as a static pressure regulator for ink entering the ink jets of the print head of an ink jet printer.
Impulse type ink jet printers have special ink supply requirements since the usual re-supply mechanism for replacing expelled ink is through capillary action and the ink supply pressure must be within the range of capillary pressure that can be generated by the print head nozzles of the ink jet printer. Since the ink reservoir is typically connected to the print head to provide the low hydrostatic supply pressure, the system is vulnerable to pressure surges generated by the motion of the print head or the supply line due to inertial forces. Thus it is desirable to keep the ink supply source at the same relative level as the ink jets of the print head when they are moved. Inasmuch as the ink supply systems heretofore utilized are generally bulky in nature, it becomes difficult to adjust the ink supply system to the movement of the printhead so as to maintain the necessary pressure requirements to provide the desired printing properties. In addition, the usual arrangement of an impulse ink jet printer is to supply a plurality of droplet ejection devices connected to the same ink supply system. With the presently existing systems of high volume ink jet mechanisms, the link of the re-circulation system to the ink supply and the location of the large ink supply containers contribute further to the difficulty of maintaining the necessary pressure requirements. Heretofore it has become necessary as a result of these disadvantages to isolate the individual ink jet devices from each other, so that they could be independently actuated. Furthermore, all ink jet printing systems function best when there is no air or gas in the lines of the ink supply system or the printhead. This requirement is particularly severe for impulse printers since air bubbles will counteract the incompresible properties of the fluid and prevent the impulse mechanism from working properly. Various techniques to eliminate this problem such as providing special chambers for the air bubbles before they reach the printhead or removing the air from the ink supply before it is used, have been proposed. However, due to the presently existing configurations, these approaches require additional and complicated system adjustments which detract from the overall effectiveness and compactness of the ink jet printer. In addition, with many prior ink jet printers the systems are tuned uniquely for each print head particularly due to the fact that the ink supply is generally bulky and thus must be positioned at a remote location from the print head. This makes adjustments, such as replacement of the print head, difficult and expensive and restricts the movement of the print head within the system when desired, thus further deminishing the flexibility of the specific ink jet printer.
Therefore, it is an object of the present invention to provide an ink supply system for an ink jet printer which will overcome the above stated disadvantages.
It is a further object of the present invention to provide an ink supply system for an ink jet printing device which acts as a static pressure regulator for the ink introduced into the ink jets of the respective printing heads.
Another object of the present invention is to provide a compact ink supply system which simplifies any mechanism necessary to keep the ink which is provided to the print head at the same relative level as the ink jets.
Yet, still another object of the present invention is to provide an ink supply system which allows for the utilization of a high capacity ink container which can be positioned at a remote location from the site of the printhead of the ink jet printer.
A further object of the present invention is to provide an ink supply system capable of supplying an array of ink jets approximately at the same elevation and which is also adaptable to serve a single ink jet.